HTTPBuilder was written by Tom Nichols ( LinkedIn profile). The code is available under the open-source ASF 2.0 license. This allows unrestricted use of the code; modification and distribution in both commercial and non-commercial products.
If you feel HTTPBuilder has been particularly helpful to you, or would like special support, please consider a donation. For general support questions, you can use the groovy-user mailing list. For more specific questions you can contact me directly as well.
Thanks and enjoy!